Spool Valve Coupling Structure for Misalignment-Tolerant Position Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing multiple direction switching valve suffers from misalignment between the motor output shaft and spool, leading to increased sliding resistance and deteriorated position controllability due to coaxial arrangement, which results in poor positional accuracy and assembly challenges.
Innovation Solution
A spool valve design incorporating a coupling member, such as a ball joint, that allows tilt and eccentricity of the spool relative to the linear-motion member, absorbing misalignment and reducing friction, coupled with a biasing mechanism for reproducible movement, enabling precise positioning and low manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the output shaft of the motor and the spool are coaxially arranged, then the structure is simple and assembly is straightforward, but misalignment occurs during assembly leading to increased sliding resistance and deteriorated position controllability
Solution Approach 1:
A coupling member is introduced as an intermediary component between the linear-motion member and the spool. This coupling member includes a coupling portion that can tilt relative to the spool, serving as a mediator that absorbs misalignment while transmitting linear motion. The coupling member has a tilting degree of freedom that allows it to compensate for assembly errors without compromising the precision of spool positioning.
2Device complexity
If the spool is directly coupled to the linear-motion member, then the structure is simple, but misalignment causes the spool to be pressed against the housing increasing friction and reducing controllability
Solution Approach 1:
The coupling member is designed with dynamic tilting capability rather than being a fixed rigid connection. The coupling portion can tilt within a certain range to adapt to misalignment conditions, dynamically adjusting its orientation to maintain optimal contact with the spool and avoid pressing the spool against the housing, thereby reducing sliding resistance.
3Manufacturing precision
If high positional accuracy is achieved through precise coaxial alignment, then position controllability improves, but assembly difficulty and manufacturing cost increase
Solution Approach 1:
The coupling member introduces a degree of freedom (tilting parameter) that changes the system's kinematic parameters. By allowing the coupling portion to tilt, the system can achieve accurate spool positioning without requiring extremely precise coaxial alignment during assembly, effectively decoupling the assembly precision requirement from the final positioning accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the deterioration of position controllability due to misalignment, enhances positional accuracy, and simplifies assembly by allowing the spool to move without bending moments, reducing friction and improving control accuracy while maintaining a simple structure and low manufacturing costs.
Implementation Method 1
the coupling member being constituted by a ball joint including a motor-side coupling portion provided at the linear-motion member, a spool-side coupling portion provided at the spool, and a ball interposed between the motor-side coupling portion and the spool-side coupling portion to couple the motor-side coupling portion and the spool-side coupling portion
Implementation Method 2
an output shaft of an electric motor is coupled to a spool through a ball screw reduction gear. When the output shaft of the electric motor rotates, the spool moves in an axial direction thereof
Data Source
AI summary
A spool valve capable of suppressing deterioration of position controllability of a spool due to misalignment includes: a housing including a spool hole; a spool inserted into the spool hole of the housing so as to be movable in an axial direction; and an electric actuator configured to move the spool in the axial direction. The electric actuator includes: an electric motor configured to rotate an output shaft; a linear-motion converting mechanism including a linear-motion member configured to be linearly movable, the linear-motion converting mechanism being configured to convert a rotational motion of the output shaft into a linear motion of the linear-motion member; and a coupling member coupling the linear-motion member and the spool moves in accordance with the linear motion of the linear-motion member. The coupling member allows one of tilt and eccentricity of an axis of the spool relative to an axis of the linear-motion member.